Measurement Computing Serial488/4 - Manual (Page 27)

Section 2 Getting Started
2.15
PRINT#1,"OUTPUT0800;P4A1B10C1D1X"
Select port 4 and specify
2 stop bits 19200 baud, no
parity, and 8 data bits
2.5.3 Handshake Configuration
The Serial488/4 uses handshaking to prevent loss of data while both
transmitting and receiving serial data. The function of handshaking is to
prevent a sender from transmitting more data than a receiver can accept.
The Serial488/4 accomplishes this in one of tw o ways, by using hardware
or software handshaking.
Hardware handshaking utilizes the Request to Send ( RTS) line of the
serial interface to inform the connected device that the Serial488/4 is able
to accept data. Inversely the Clear to Send (CTS) line of the serial interface
is monitored by the Serial488/4 to determine w hether or not the connected
device is able to accept data. The Serial488/4 may be configured to use the
hardware (RTS/CTS) handshaking method w ith the G0 command. In
addition the automatic handshaking control option (N0) is normally used.
This option will negate and assert the RTS line depending on the amount of
memory available for receiving serial data. The manual handshake control
options, N1 and N2, may be used in special circumstances to un-assert
and assert the RTS line under program control if desired. The clock output
handshake control option (N3) is not allowed when hardware handshaking
is being used and will generate a command conflict error if attempted.
The software handshaking method uses special control characters,
transmitted along with the serial data, to prevent loss of serial data. The
XOFF
character (&H11) is transmitted to inform the connected device that
the Serial488/4 is no longer able to accept data. The XON character
(&H13) is transmitted to inform the connected device that the Serial488/4
is again able to accept data. Similarly the Serial488/4 monitors the serial
data it receives for the occurrence of XON/XOFF control characters and
stops or starts the transmission of data to the connected device accordingly.
The Serial488/4 may be configured for software (XON/XOFF) handshaking
by using the G1 command. In addition the automatic handshaking control